'Once' in the Bible

Now therefore forgive, I pray thee, my sin only this once, and intreat the LORD your God, that he may take away from me this death only.

And Aaron shall make an atonement upon the horns of it once in a year with the blood of the sin offering of atonements: once in the year shall he make atonement upon it throughout your generations: it is most holy unto the LORD.

The Lord spoke to Moses: “Go down at once! For your people you brought up from the land of Egypt have acted corruptly.